The present invention relates to a housing structure of a turbomachine and a corresponding turbomachine with such a housing structure in accordance with the present invention.
In turbomachines, such as stationary gas turbines or aircraft engines, the flow duct through which flows the fluid with which the turbomachine is operated, is delimited by a housing structure, which, on account of the conditions prevailing in the flow duct, has to meet diverse requirements. Because in part very high temperatures usually occur in the flow duct, the housing structure outwardly surrounding the flow duct has to ensure, in particular, that the temperature differences between the flow duct and the surroundings can be maintained, without the housing being heated too strongly on the outside. Accordingly, the housing structure usually has at least a two-shelled structure with an inner housing wall and an outer housing wall, which, on account of their different spacings from the flow duct, are subjected to temperature loads of different magnitude. In the gap between the outer housing wall and the inner housing wall, it is possible to provide thermally insulating elements and heat protection shields and the gap can also serve to carry a cooling fluid, such as cooling air. The design of the housing structure can be correspondingly complex.
Examples of housing structures of this kind are presented in U.S. Pat. No. 5,145,316 A or WO 2015/084550 A1. In the housing structure such as that shown in U.S. Pat. No. 5,145,316 A, however, there is a problem in that, owing to a direct attachment of the inner housing wall, which is in contact with the hot gas carried in the flow duct and is formed in the region of the rotating blades by a so-called outer fluid seal (outer air seal, OAS), to the outer housing wall, a strong thermal conduction into the outer housing wall takes place and a there is a high thermal output into the outer housing wall, so that the outer housing wall is subjected to a high temperature load.
In the housing structure of WO 2015/084550 A1, a heat protection shield is provided in the housing in the region of the rotating blades between the OAS of the inner housing wall and the outer housing wall and is arranged at a spacing from the OAS and from the outer housing wall. As a result of this, an additional shielding of the outer housing wall against the temperature load due to hot fluid in the flow duct can be achieved. However, the heat shielding is limited by the spaced arrangement of the heat protection shield from the OAS, and the design is complex, in particular for carrying cooling air, owing to the provision of a plurality of gaps in the radial direction between the OAS and the outer housing wall. Moreover, the heat protection shield is additionally mounted at the outer housing wall, so that, here, too, outward thermal conduction can occur.